How can I export FBX with physics?
Depends on what you mean by 'physics'…


If it’s advanced things like particles, soft bodies etc., then answer is quite simple - you cannot export those. Only thing that is supported to some extent are object/group instances over a particle system.
If it’s exporting real time (rigidbody &amp; co) physics settings (weight, bounciness, collision shells, etc.), you cannot really do that either (though you could define required parameters as custom properties, and use those custom props when you import your FBX, but nothing working “out of the box”).
If it’s exporting the results of some rigidbody physical simulation, then you have nothing to do, it will be baked as part of the scene's animation during FBX export.